Cash, Cash Equivalents and Investments (Details 2) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 28, 2013	Dec. 29, 2012
Short-term investments
Amortized Cost	$ 95,690	$ 100,170
Gross Unrealized Gains	345	545
Gross Unrealized Losses	(16)	(11)
Fair Value	96,019	100,704
Corporate debt securities [Member]
Short-term investments
Amortized Cost	36,859	31,313
Gross Unrealized Gains	33	57
Gross Unrealized Losses	(14)	(11)
Fair Value	36,878	31,359
Bank certificates of deposit [Member]
Short-term investments
Amortized Cost	18,300	27,805
Gross Unrealized Gains	13	21
Gross Unrealized Losses	0	0
Fair Value	18,313	27,826
US Treasury Securities [Member]
Short-term investments
Amortized Cost	24,705	23,213
Gross Unrealized Gains	34	26
Gross Unrealized Losses	(1)	0
Fair Value	24,738	23,239
US Government Corporations and Agencies Securities [Member]
Short-term investments
Amortized Cost	11,215	10,245
Gross Unrealized Gains	13	13
Gross Unrealized Losses	(1)	0
Fair Value	11,227	10,258
Commercial paper [Member]
Short-term investments
Amortized Cost	2,794	5,777
Gross Unrealized Gains	3	6
Gross Unrealized Losses	0	0
Fair Value	2,797	5,783
Marketable debt securities [Member]
Short-term investments
Amortized Cost	93,873	98,353
Gross Unrealized Gains	96	123
Gross Unrealized Losses	(16)	(11)
Fair Value	93,953	98,465
Marketable equity securities [Member]
Short-term investments
Amortized Cost	1,817	1,817
Gross Unrealized Gains	249	422
Gross Unrealized Losses	0	0
Fair Value	$ 2,066	$ 2,239